alpine deck 2 sets of alpine 6-1/2 inch componants type R
2 x type R 12s dual 2 ohm
one MTX 8100d
MTX 4 channel 100 x 4
all of that in a full size bronco = 151 db
and it has the best SQ iv heard in a long time

2) Four Infinity 63.5i speakers (door mounted unfortunately) powered by the deck with a -12dB/octave cutoff at 160Hz. You could get away with two only and properly mount them using Q-Logic kick panel enclosures (my next spring project). They'll handle much more than the Pioneer deck can put out but see the following SPL measurement!

3) Two Infinity Basslinks mounted vertically right behind the back beach seat firing towards the rear hatchback of the vehicle with one switched to 180 phase (as I wanted them to be mounted "symmetrically" looking) and they're using the deck's -18dB/octave cutoff at 80Hz. The long path the bass travels has seemed to improve very low bass response.

Why such a difference in cutoff frequencies (80Hz and 160Hz)??? If I went closer together, it sounded much too boomy and loud at those frequencies so that was the separation I needed to get a satisfying flat response believe it or not.

The sound is more accurate and tighter than anything else I've heard (in a vehicle that is) and according to the SPL meter, it does more than 126dBspl (as that's the meter's maximum) without any noticeable distortion. So, that's good enough for me. And, yes, I can actually feel the bass. There have been kick drums that made me think I got rear-ended and made me check my rear-view mirror. Also good is that the GC's construction is so darn thick that not much sound escapes the vehicle's interior to bother others around me, heh.